The federal agents make a big deal of the suite being very secure, with bulletproof glass everywhere. TJ shoots out the glass easily when he mistakes the window washer for a Hitman. One-way bulletproof glass exists, but 1. Why would they need to install that, to shoot outwards in a safe house 12 floors above every other building around (as stated in the show)? When even the window washer was vetted by the FBI, 2. Why couldn't they wait two weeks to wash the windows, 3. One-way bulletproof glass shatters outward, so shrapnel doesn't come flying back into the protected side.
There *are* size B batteries (as well as size A). They did not find as many uses as the now-common AA, AAA, C, and D, but they do exist and can be bought at specialty electronic stores as well as online.